JP2002030954A - Prime mover revolution control device for hydraulic running vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a steering operation force generated during starting of running, responsiveness, acceleration performance, or a steering operation force generated during deceleration, and cavitation without worsening fuel consumption in an idle state during a work. SOLUTION: The revolutions of prime mover control device comprises a discriminating means 24B to discriminate a running state and a working state; and a number of idle revolutions setting means 24C to set the rather high idle revolutions suitable for running when running is detected and set rather low revolutions suitable for a work when a working state is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for controlling the rotation speed of a motor of a hydraulic traveling vehicle having a traveling hydraulic motor and a work actuator.

[0002]

2. Description of the Related Art As this kind of motor rotation speed control device,
One disclosed in Japanese Utility Model Laid-Open No. 61-97457 is known. In this motor rotation speed control device, when the travel pedal is depressed, the travel flow control valve is opened and the engine speed is controlled in accordance with the amount of depression. When the travel pedal is not operated, the engine is operated at a predetermined idle speed.

[0003] On the other hand, a motor rotation speed control device disclosed in Japanese Patent Application Laid-Open No. 62-225727 is also known.
This prime mover control device determines whether the vehicle is running or excavating, or is interrupting the operation.When the traveling pedal is not depressed or the work lever is not operated during the operation, the engine idle speed is determined. The first idle speed is set to be higher than the allowable minimum speed (the minimum speed at which the engine does not stall), and the engine idle speed is set to the second idle speed corresponding to the allowable minimum speed during work interruption. Is set to

[0004]

However, in the case where the former motor speed control device disclosed in Japanese Unexamined Patent Publication No. 62-225727 is applied to the former motor speed control device disclosed in Japanese Utility Model Application Laid-Open No. 61-97457, there is a problem. The method of setting the idle speed of 1 is very delicate, and there is a problem if it is too low or too high.

[0005] That is, if a value suitable for traveling is selected as the first idle speed, fuel efficiency during work deteriorates, and a prime mover speed with good fuel efficiency during work is selected as the first idle speed. The following problems occur. When the steering operation is performed at the time of starting, if the steering operation angle is large, the flow rate becomes insufficient and the steering operation becomes heavy. If the pump flow rate is small at the time of starting, responsiveness is poor due to the override characteristics of the pilot relief. During deceleration, the pump flow rate may decrease, and the steering operation force may suddenly become heavy. Cavitation may occur during deceleration. Since the engine output torque is small in the low rotational speed range, the dragging phenomenon of the engine occurs during acceleration, resulting in poor acceleration. Black smoke is generated during the above operation.

An object of the present invention is to provide a prime mover rotation speed control apparatus for a hydraulic traveling vehicle that solves the above-mentioned problems that occur during traveling without deteriorating fuel consumption during work.

[0007]

The present invention will be described with reference to FIG. 1 which is a claim correspondence diagram and FIGS. 3 to 5 which show an embodiment. The present invention relates to a hydraulic pump 1 driven by a prime mover 21, A traveling hydraulic motor 4 driven by oil discharged from the pump 1, a working actuator 52 driven by oil discharged from the hydraulic pump 1, and an operation for controlling hydraulic oil supplied to the hydraulic motor 4 and the actuator 52 Means 6 and the prime mover 2 according to the operation amount of the operation means 6
The present invention is applied to a prime mover rotational speed control device of a hydraulic traveling vehicle including a rotational speed control means 24A for controlling the rotational speed of the motor. Then, a discriminating means 24B for discriminating between the traveling state and the working state according to the vehicle state, and when the traveling state is discriminated, a higher idle speed (Nti in FIG. 5) suitable for traveling is set. And an idle speed setting means 24C for setting a lower idle speed (Ndi in FIG. 5) suitable for the work when the discrimination is made, and the speed control means 24A operates other than the operation means (26a, 26b). A first setting means for setting a first target rotation speed (Na in FIG. 4) to be increased or decreased by a second setting, and a second setting for a second target rotation speed (Nb in FIG. 5) to be increased or decreased by the operation means 6 When the operating means 6 is not operated, the idle speed setting means 24C
Controlling the prime mover speed to the larger of the idle speed and the first target speed set by
The above object is achieved by controlling the prime mover rotational speed to the larger one of the first target rotational speed and the second target rotational speed when operating the operating means 6. Claim 2
The present invention includes idle shift means (step S12 in FIG. 4) for controlling the rotation speed of the prime mover to an idle rotation speed according to the working state when the idle switch 26c is operated.

[0008]

When the engine speed is controlled by the operating means 6, the idle speed is set lower during operation and higher than that during running. The engine speed when the operation means 6 is not operated is controlled to the larger one of the idle speed and the first target speed which is increased or decreased by an operation other than the operation means (26a, 26b). .

Incidentally, in the section of the means for solving the above-mentioned problem and the section of the operation which explain the constitution of the present invention, the drawings of the embodiments are used in order to make the present invention easy to understand. It is not limited to the embodiment.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a wheel type hydraulic excavator will be described with reference to FIGS. 2 and 3 show a traveling hydraulic circuit and an engine speed control device of a wheel type hydraulic excavator. In the present embodiment, the engine speed at the time of work can be controlled by a depression operation of a traveling pedal. The engine idling speed set when the pedal is not operated is low during work and high during running.

In FIGS. 2 and 3, an engine (motor) 2
The oil discharged from the hydraulic pump 1 driven by the hydraulic pump 1 is guided to a traveling hydraulic motor 4 via a counterbalance valve 3 via a hydraulic pilot control valve 2. The control valve 2 includes a hydraulic pump 5, a pilot valve 6,
The switching is controlled by a pilot hydraulic circuit comprising a slow return valve 7 and a forward / reverse switching valve 8.

A governor 21a of the engine 21 is connected to a pulse motor 23 via a link mechanism 22, and the rotation of the pulse motor 23 controls the rotation speed of the engine 21. That is, the rotation speed increases with the forward rotation of the pulse motor 23 and decreases with the reverse rotation. The rotation of the pulse motor 23
It is controlled by a control signal from the controller 24. A potentiometer 25 is connected to the governor 21a.
The potentiometer 25 detects a governor lever position corresponding to the rotation speed of the engine 21 and inputs the governor lever position detection value Nrp to the controller 24.

The controller 24 also includes an engine speed up switch 26 provided on the console of the cab.
a, an engine speed down switch 26b, and an idle switch 26c for shifting the engine speed to the idle speed at a stretch. Further, an n terminal of the forward / reverse switch 27 and a W terminal of the brake switch 28 are connected, and a pressure sensor 29 provided in a pipeline between the pilot valve 6 and the forward / backward switch valve 8 is connected. . The pressure sensor 29 detects a pilot pressure Pi generated in proportion to the operation amount of the travel pedal 6a and inputs the pilot pressure Pi to the controller 24. The pilot pressure Pi indicates the pedal operation amount θp, and is used for controlling the engine speed as described later.

The common terminal of the forward / reverse selector switch 27 is connected to the battery 30, and the f and r terminals are also connected to the solenoid of the forward / reverse selector valve 8 via the normally closed contacts RS1 and RS2 of the relay R. The forward / reverse switching valve 8 is switched to the N, F, and R positions with the switching to the f and r positions. When the forward / reverse switch 27 is operated to the f position, the forward / backward switching valve 8 is switched to the F position, when it is operated to the r position, it is switched to the R position, and when it is operated to the n position, it is switched to the N position. .
When the forward / reverse selector switch 27 is in the n position, the controller 2
4 is input with a high level signal indicating a neutral state.

When the traveling pedal 6a is operated with the forward / reverse switching valve 8 switched to the F position (forward position) or the R position (reverse position), the discharge pressure of the hydraulic pump 5 is controlled by the pilot valve 6, and the operation of the pedal 6a is performed. Is guided to the pilot port 2a or 2b of the control valve 2 via the slow return valve 7 and the forward / reverse switching valve 8. At this time, control valve 2
Is switched in a predetermined direction by a predetermined amount. Of the discharge oil of the hydraulic pump 1 that rotates according to the operation amount of the travel pedal 6a, only the amount corresponding to the switching amount of the control valve 2 is guided to the hydraulic motor 4. As a result, the hydraulic motor 4 is driven and the travel pedal 6
The vehicle moves forward or backward at a speed corresponding to the operation amount a.
At this time, the engine speed is also increased or decreased according to the operation amount of the travel pedal 6a as described later.

The brake switch 28 is operated by the operator when the vehicle is running, parking, or working. The common terminal is connected to the battery 30 and the W terminal is connected to the controller 24. Also this brake switch 2
8 W terminal is also connected to the relay coil RC,
As the switch 28 is switched to the W position, the relay coil RC is excited. When the coil RC is excited, the above-described normally closed contacts RS1 and RS2 are opened. In this state, the forward / reverse switch 27 and the forward / reverse switch valve 8 are shut off, and even if the switch 27 is operated to the f position or the r position. The forward / reverse switching valve 8 holds the neutral position N. In addition, W (work) terminal,
The T (running) terminal and the P (parking) terminal are respectively connected to a solenoid unit of a solenoid valve (not shown). When the W terminal is operated, the parking brake and the service brake are operated,
When the terminal is operated, only the service brake becomes operable, and when the terminal is operated, the parking brake is operated.

The oil discharged from the hydraulic pump 1 is guided to a working hydraulic cylinder 52 via a control valve 51. And the working lever 51a
By operating the control valve 51 to extend and retract the cylinder 52,
Thereby, the work attachment is driven to perform the work. During this operation, the traveling pedal 6 is operated as described later.
a, the engine speed can be controlled, and finer control (fine adjustment) can be performed than when the speed control is performed by the up / down switches 26a, 26b. Noise can be prevented without undesirably increasing the engine speed. It contributes to improved fuel efficiency.

Next, the control of the engine speed by the controller 24 will be described with reference to the processing procedures of FIGS. First, in step S1, the governor lever position target value Nro, the up switch 26a, the down switch 26b
, The idle signal from the idle switch 26c, the governor lever position detection value Nrp input from the potentiometer 25, and the operation amount θp of the traveling pedal 6a, which is the detection value of the pressure sensor 29.

In step S2, it is determined whether or not the idle switch 26c is turned on.
In step 12, Ndi is substituted for the target rotational speed Na by the up / down switch, and the process proceeds to step S13.

If it is determined in step S2 that the idle switch 26c is off, the operation proceeds to step S3. Step S3
Proceeds to step S4, the presence or absence of a DOWN signal is determined. If the result is affirmative, the process proceeds to step S4. If the result is negative, that is, if the down switch 26b is on, the process proceeds to step S5. . In this step S5, a governor lever position target value Na calculated by an up / down switch previously calculated and stored in a memory, and a rotational speed increase / decrease amount △ Nr which is predetermined as an increase / decrease amount of the engine rotational speed are determined in advance. Minimum engine speed Nr
Using min, it is determined whether or not Na− △ Nr> Nrmin. If affirmative, in step S7, Na- △ Nr is stored in the memory as a new governor lever position target value Na. If Na- △ Nr ≦ Nrmin, the routine proceeds to step S6, where Nrmin is stored in the memory as a new governor lever position target value Na.

On the other hand, if step S3 is negative, it is determined in step S8 whether there is an UP signal. If affirmative, in step S9, the governor lever position target value Na
Then, it is determined whether or not Na + △ Nr <Nrmax using the rotational speed increase / decrease amount △ Nr and a predetermined maximum engine speed Nrmax. If affirmative, in step S11, Na + △ Nr is stored in the memory as a new governor lever position target value Na. If Na + △ Nr ≧ Nrmax, Nrmax is stored in the memory as a new governor lever position target value Na in step S10.

In step S13, it is determined whether the vehicle is running or working. This determination can be made as follows. That is, when the forward / reverse selector switch 27 is other than the n position and the brake switch 28 is other than the W position, the traveling state is determined.

If the vehicle is in the running state, the process proceeds to step S14. If the vehicle is in the working state, the process proceeds to step S15. In step S14, the target rotation speed Nt by the pedal is read from the rotation speed characteristics suitable for traveling based on the travel pedal depression amount θp, and in step S16, the target rotation speed Nt is substituted for the target rotation speed Nb. In step S15, a target rotation speed Nd by a pedal suitable for the work is read based on the travel pedal depression amount θp. Then, in step S17, the target rotation speed Nd is substituted for the target rotation speed Nb. Here, the idling speed Nti during traveling> idling speed Ndi during work
Is set to

Further, in step S18, the magnitude relationship between the target rotation speed Nb by the pedal and the target rotation speed Na by the up / down switch is determined.
In step 20, a large value is substituted as the target rotation speed Nro. Thereafter, the process proceeds to step S21.

In step S21, the result of Nrp-Nro is stored in the memory as a rotational speed difference A, and in step S22, using a predetermined reference rotational speed difference K, | A | ≧ K
It is determined whether or not. If affirmative, the process proceeds to step S23, where it is determined whether or not the rotational speed difference A> 0. If A> 0, the governor lever position detection value Nrp becomes the governor lever position target value Nro.
In other words, since the control speed is higher than the target speed, step S2 is performed to reduce the engine speed.
In step 4, a signal for instructing the motor to rotate in reverse is output. If A.ltoreq.0, the governor lever position detection value Nrp is smaller than the governor lever position target value Nro, that is, since the control rotation speed is lower than the target rotation speed. Output a signal. If step S22 is denied, the process proceeds to step S26 to output a motor stop signal. After executing steps S24 to S26, the process returns to the beginning.

According to such a processing procedure, the engine speed is controlled as follows. When the engine speed is controlled by the travel pedal, a higher idle speed Nti is set when the travel pedal 6a is not operated at the time of running determination, and a lower idle speed Ndi is set when the travel pedal 6a is not operated at the time of work determination.
Is set. When the idle switch 26c is turned on, the idle speed Ndi for work is controlled to Ndi. When the up switch 26a or the down switch 26b is turned on / off instantaneously only once; When the up switch 26a is turned on / off instantaneously only once, a pulse-like UP signal is output from the up switch 26a.
As a result, since step S11 is executed only once,
If Na + ΔNr is less than the maximum rotational speed Nrmax, a governor lever-position target value Na which is increased by ΔNr with respect to the governor lever position target value Na by the up / down switch previously calculated and stored in the memory is calculated. Since the governor lever position target value Na by the up / down switch is used as Nro, this value Nro and the governor lever
If the difference | A | from the position detection value Nrp is greater than or equal to the reference rotational speed difference K and A is negative, a motor forward rotation command signal is output, and the pulse motor 22 is rotated forward by the motor forward rotation command signal.
As a result, the pulse motor 22 rotates forward and the link mechanism 22 rotates.
When the governor 21a is driven through the engine, the engine speed increases. The rotation amount of the pulse motor 22 is detected as a governor lever position detection value Nrp, and the governor lever position detection value Nrp and the governor lever position target value N after driving the motor.
When the difference | A | with respect to ro becomes smaller than the reference rotational speed difference K, a motor stop signal is output and the pulse motor 22 stops.

When the down switch 26b is turned on and off instantaneously only once, the engine speed is similarly reduced.

When the up switch 26a or the down switch 26b is continuously operated for a predetermined time; when the up switch 26a is continuously operated for a predetermined time, a high level UP signal is output from the up switch 26a for a predetermined time. Since the process of FIGS. 4 and 5 is performed a plurality of times (for example, Q times) within the time when the UP signal is at the high level, the governor lever-position target value Na becomes Na + Q △ Nr. If this value is smaller than Nrmax, this Na + Q △ Nr is equal to the new governor lever.
The position target value Na is stored in the memory, and the pulse motor 22 is rotated forward until | A | ≧ K is denied, as described above.

In the configuration of the above embodiment, the controller 24 constitutes the rotational speed control means 24A, the discriminating means 24B and the idling rotational speed setting means 24C, and the traveling pilot valve 6 constitutes the operating means. The control valve 2 is an electromagnetic proportional valve, an electric operation member for outputting an electric signal according to the amount of depression of a travel pedal is provided, and the control valve and the engine speed are controlled by the electric signal. Can be applied. Further, the discrimination between the running state and the working state may be other than the above-described method. For example, the running state may be determined if the foot is in contact with the running pedal, and the working state may be determined if the working lever is touched by the hand. Further, the present invention is applied to various work vehicles other than the wheel hydraulic excavator.

[0030]

According to the present invention, the idle speed is automatically switched according to the vehicle condition, so that the idle speed switching operation by the operator is not required. In addition, since the idling speed during traveling is set to be higher than during operation, the following effects can be obtained during traveling without deteriorating fuel efficiency during operation. When the steering operation is performed at the time of starting, even if the steering operation angle is large, the flow rate is not insufficient and the steering operation can be performed lightly. At the time of start, the pump flow rate is increased, and deterioration of responsiveness due to the override characteristic of the pilot relief can be prevented. Since the pump flow rate during deceleration is large, the steering operation force does not suddenly become heavy. Cavitation during deceleration can be prevented. No engine dragging phenomenon occurs during acceleration, and the acceleration is improved. Further, since the idle speed can be set higher by an operation other than the operation means, it is possible to work at a desired speed while the operation means is not operated during the operation. Furthermore, at the time of traveling, the vehicle can travel at a desired rotational speed without operating the operation means. Furthermore, when such a high idle speed is set,
By operating the idle switch, the idle speed can be easily changed to a predetermined low value.

[Brief description of the drawings]

[Fig. 1] Claim correspondence diagram

FIG. 2 is a diagram showing a part of a prime mover speed control device and a hydraulic circuit according to the present invention;

FIG. 3 is a diagram showing the remaining portion of the prime mover speed control device and the hydraulic circuit according to the present invention;

FIG. 4 is a flowchart showing a part of an engine speed control process executed in the controller shown in FIG. 3;

FIG. 5 is a flowchart showing the remaining part of the engine speed control process executed in the controller of FIG. 3;

[Explanation of symbols]

 Reference Signs List 1 hydraulic pump 2 control valve 4 hydraulic motor 6 traveling pilot valve 6a traveling pedal 7 slow return valve 8 forward / reverse switching valve 21 engine 21a governor 24 controller 24A rotation speed control means 24B discriminating means 24C idle speed setting means 25 potentiometer 26a up Switch 26b Down switch 26c Idle switch 27 Forward / reverse selector switch 28 Brake switch 29 Pressure sensor

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F15B 11/00 F15B 11/00 E (72) Inventor Kazuo Asano 650, Kandamachi, Tsuchiura-shi, Ibaraki Pref. Hitachi Construction Machinery Inside the Tsuchiura Plant, Ltd. DA00 DA06 DA10 DB11 DB15 EA03 EC02 FA07 3G301 HA28 JA02 JA03 KA07 LB14 LC03 NA06 NC01 NC07 ND02 NE01 NE06 PB04 PF00 PF03 PF05 PF08 PF11 3H089 BB01 BB11 BB14 CC01 CC08 DA13 DB09 DB32 EE36 EE39 FF12

Claims (2)

[Claims] 1. A hydraulic pump driven by a prime mover, a traveling hydraulic motor driven by oil discharged from the hydraulic pump, a working actuator driven by oil discharged from the hydraulic pump, and the hydraulic motor And an operating means for controlling pressure oil supplied to the actuator and a rotational speed control means for controlling the rotational speed of the prime mover. Determination means for determining the state of the vehicle; and an idle for setting a higher idle speed suitable for traveling when the traveling state is determined, and setting a lower idle speed suitable for the operation when the operation state is determined. Rotation speed setting means, wherein the rotation speed control means sets a first target rotation speed which is increased or decreased by an operation other than the operation means. And a second setting means for setting a second target rotation speed which is increased or decreased by the operation means, wherein the idle speed set by the idle speed setting means when the operation means is not operated. And controlling the prime mover rotation speed to the larger one of the first target rotation speeds, and operating the operating means, the first target rotation speed and the second target rotation speed A motor rotation speed control device, wherein the motor rotation speed is controlled to a higher rotation speed. 2. The motor speed control device for a hydraulic traveling vehicle according to claim 1, wherein said speed control means changes said motor speed to an idle speed corresponding to said working state when an idle switch is operated. An engine speed control device, comprising: an idle shift means for controlling the engine speed.